Hazards of Merapi
The island of Java has more than 600 people per square km, one of the
highest population densities in the world. Yogyakarta city, with a
population of 3 million, is 15 miles (25 km) south of Merapi. About 70,000
people live in the immediate vicinity of the volcano.
Merapi is a basaltic to basaltic-andesite stratovolcano with a summit crater
containing an unstable lava dome. Merapi is Indonesia's most active volcano
and well known for partial collapse of lava domes and the generation of
pyroclastic flows. Pyroclastic flows can travel as far as 8 miles (13 km)
from the summit and reach speeds of 70 mph (110 km/hr). Pyroclastic flow
deposits can be remobilized as lahars. Direct observations of Merapi have
been recorded since 1888. Recent study of tephra deposits on the flanks of
the volcano found 27 marker beds that reveal Merapi's past history. The
volcano has had numerous moderate to large (1 million cubic m) eruptions.
These eruptions typically begin with pyroclastic flows and are followed by
widespread pyroclastic air fall. Plinian to subplinian eruptions are
common. These older deposits indicate that Merapi is capable of eruption
styles very different from those currently observed.
Andreastuti, S.D., Alloway, B.V., and Smith, I.E.M., 1997, A detailed tephrostratigraphy at Merapi volcano, central Java: Implication for eeruption prediction and hazard assessment, in Program and Abstract, 2nd Merapi Decade Volcano International Workshop, Yogyakarta, VSI-UNESCO, p. 26.
Purbawinata, M.A., Ratdomopurbo, A., Sinulingga, I.K., Sumarti, S., Suharno, 1996, Merapi volcano a guide book: Volcanological Survey of Indonesia, Bandung, 64 p.
Suryo, I. and Clarke, M.C.G., 1985, The occurrence and mitigation of
volcanic hazards in Indonesia as exemplified at the Mount Merapi, Mount
Kelut, and Mount Galunggung volcanoes: Q.J. Eng. Geol. London, v. 185, p.